BUFFALO: Offensive coordinator Nathaniel Hackett brought a much different look to the Bills' running game in his first season with the team in 2013, and it didn't do C.J. Spiller any favors. Buffalo uses a lot of read option plays to try to take advantage of quarterback EJ Manuel's mobility. Spiller was hesitant in read-option situations, and Manuel was fragile as a rookie, so they might move back to a more traditional look this year. Spiller figures to take back more of a No. 1 workload from Fred Jackson, though that was the plan a year ago and Jackson proved too valuable to keep off the field. Bryce Brown provides insurance for the aging Jackson. In the red zone, the Bills quickly moved away from Spiller in goal-to-go situations, opting for Jackson's more decisive running instead.
Hackett uses play-action and crossing action in the middle of the field. Rookie Sammy Watkins will likely be penciled in at flanker, where they'll rely on his YAC ability to make Manuel's life easier. After spending the early part of the year on the perimeter last year, No. 2 WR Robert Woods should work a larger set of routes, similar to what former No. 1 receiver Stevie Johnson used to run. Marquise Goodwin figures to overtake T.J. Graham as their primary deep threat, while Mike Williams comes in as a red zone specialist. Tight end Scott Chandler will be utilized as a receiver underneath.
The Bills will be playing for their third defensive coordinator in three years with Jim Schwartz replacing Mike Pettine, who improved this group a lot in 2013, especially with sacks and interceptions. Free agent outside linebackers Keith Rivers and Brandon Spikes will greatly help Buffalo's transition to a 4-3 scheme.

CHICAGO: Aaron Kromer is both the offensive coordinator and offensive line coach, though head coach Marc Trestman handles the play-calling duties. This is a versatile running game that shows a lot of different looks and styles. They're at their best with fullback Tony Fiammetta leading the way for Matt Forte on inside zone runs. They'll also use some basic man concepts, with pulling guards leading the way, when they send Forte outside the tackles. It's a pass-heavy offense and will remain that way considering the lack of depth behind Forte, who will carry a huge workload with rookie Ka'Deem Carey likely to be sprinkled in.
Chicago will continue to run a pass-heavy offense under Trestman. He emphasized shorter, quicker timing routes with quarterback Jay Cutler, keeping him relatively upright and allowing his NBA-sized receivers to make plays. Cutler is able to make more pre- snap determinations, and often just puts the ball up top for either Brandon Marshall or Alshon Jeffery to bring in. The two of them work deeper downfield than most receivers. They'll use TE Martellus Bennett as a possession guy in the middle of the field once the receivers stretch out opposing defenses. They'll go three-wide sparingly. Forte will be involved heavily in the screen game and as a checkdown option.
After the Bears' horrific 2013 season of placing among the bottom-three NFL teams in sacks, points allowed and yards allowed, changes were definitely needed under defensive coordinator Mel Tucker. But new defensive ends Jared Allen and Lamarr Houston and new safeties Ryan Mundy and M.D. Jennings can only help so much.

Although the Chicago Bears possess all the makings of an elite offense, turning around their defensive incompetence appears to be a necessity if they're going to make a run at the playoffs.

After making several moves to fix those holes, the Bears hope to see major improvement on that side of the ball as they look to win their sixth straight home opener Sunday against the Buffalo Bills, who haven't been to the playoffs in 15 years.

Chicago opened 3-0 under first-year coach Marc Trestman but was inconsistent after that greatly due to a suspect defense, though the team needed to win just one of its final two games to reach the postseason for the first time since 2010. Instead, the Bears missed the playoffs despite an outstanding offensive season after allowing a combined 87 points and 987 yards in consecutive losses to Philadelphia and Green Bay.

"We're hungry," Pro Bowl cornerback Tim Jennings said of the defense. "We've got attitude from last year. The coaches feel the same way as well as the players do. ... We really still have a bad taste in our mouth from last season."

Trestman's focus was on offense and he made his mark. Chicago improved from 29th to fifth in passing and 28th to No. 8 in total offense, even with Josh McCown appearing in eight games and starting five due to Jay Cutler's groin and ankle injuries.

Cutler still posted a career-high 89.2 passer rating with his best completion percentage (63.1) since 2007 with Denver, throwing 19 touchdowns and 12 interceptions. His sack total dropped from 38 in 2012 to 19 behind a rebuilt offensive line.

Alshon Jeffery and Brandon Marshall each had Pro Bowl seasons, giving Chicago one of the best receiving tandems in the NFL. They totaled 189 receptions for 2,716 yards and 19 touchdowns, and Jeffery ranked second in the league among receivers with 1,526 yards from scrimmage.

The Bears recently added former Jets and Steelers receiver Santonio Holmes to provide some depth.

"He's exciting," Cutler said. "We've just got to get him caught up with everything right now. It's hard coming in where we are offensively and just kind of throwing him into the mix."

Matt Forte further established himself as one of the NFL's top all-purpose backs, ranking second with a career-high 1,339 rushing yards and third with 1,933 from scrimmage.

Even if its high-powered offense continues to shine, Chicago will likely miss the postseason for the seventh time in eight years unless it can recover from one of the worst defensive performances in franchise history.

The Bears ranked 30th overall, allowing 394.6 yards per game, while tying Jacksonville with a league-low 31 sacks and giving up a league-high and club-record 2,583 rushing yards.

Chicago has brought in five-time Pro Bowler Jared Allen, versatile LaMarr Houston and Willie Young to improve the line, while Julius Peppers has gone on to Green Bay.

Allen, however, has battled a bruised shoulder, first-round pick Kyle Fuller is nursing an ankle injury and fellow defensive back Chris Conte missed most of the preseason recovering from shoulder surgery before suffering a concussion.

Though they surrendered more yards per game than all but three teams during the preseason and were third worst in scoring defense, the Bears aren't worried that things won't be better on that side of the ball.

"All the additions that we brought to this defense, I'm excited about it and I just can't wait to get us all together and get us come Sunday, and see where we're at," Jennings said.

The Bears could have an opportunity to gain some confidence versus Buffalo, which had difficulty moving the ball throughout the preseason. The starters went 18 straight possessions without a touchdown until EJ Manuel's TD pass in the second half against Tampa Bay on Aug. 23.

Manuel had been tabbed the quarterback of the future after Buffalo selected him 16th overall in 2013, but many are skeptical of whether he can fulfill that promise after enduring an inconsistent, injury-plagued rookie season.

"With EJ, obviously we're looking for him to progress and to keep coming along," Marrone said. "We're going to stick with him. I'm going to support him 110 percent. And we're going to get him better."

Buffalo, which finished 6-10 last season, has just one winning season since last qualifying for the playoffs in 1999.

The Bills finished 28th in the league with 193.9 passing yards per game, though they were second with 144.2 rushing yards. C.J. Spiller and Fred Jackson combined for 1,823 yards and 11 touchdowns on the ground.

Sammy Watkins, taken fourth overall in the 2014 draft, was brought in to give Manuel a go-to playmaker in the passing game, but he's been slowed by bruised ribs. Watkins is expected to line up across from Mike Williams, acquired in an offseason trade with Tampa Bay.

Buffalo's defense should remain a strength under new coordinator Jim Schwartz after setting a franchise record with 57 sacks. The Bills added middle linebacker Brandon Spikes to a unit that gave up 150-plus yards rushing seven times.

"I don't want to get ahead of that stuff but, hey, the proof's in the pudding," Spikes said of Schwartz. "He wants us getting vertical, getting disruptive, causing havoc."

Spikes' addition should help the team recover from the loss of linebacker Kiko Alonso, who suffered an ACL injury that required surgery just after reporting to camp.

The Bills have dropped all five of their visits to Chicago by a 135-39 margin.